Ecolog:
Meiss' post really moves the ball forward in some interesting ways, and I
will be most interested in Beans' responses. If I have anything to add,
it
might be along the lines of wondering how one considers or measures the
strength (and how strength is defined or determined) of interactions the
number of generations required for genetic change, the kinds of genetic
changes that would be expected and on what basis, and what kinds of
interactions might be involved.
I wonder also just how one might tease out and identify, not only the
"other environmental changes as a result of the invasion . . .," but as
well
those not so associated.
Meiss correctly anticipated the main question that lurked in the back of
my
mind, how one would sort out the pre- and post-contact genetic
differences,
not to mention the effects of those differences.
I suspect that Meiss also is on the money with his suggestion that
ecological studies might be more productive; however, I eagerly
anticipate
Beans' responses. I do not intend to discourage Beans from following her
own
star in this, and, of course, she must be "practical" until she gets
through
the academic gauntlet. If she can do that, while simultaneously making a
name for herself without incurring the ire of those "above" her, she
should
soon be able to shift her research emphasis--if that is what the evidence
and her sense of ecology indicates. Unless her initial literature review
has
revealed a sufficient number of similar studies that have disproved the
usefulness of her design, "failure" might contribute as much as success.
Apparently it has not, or she wouldn't be pursuing this particular line.
WT
PS: While I tend to tip in favor of Meiss' suggestion about studying
distributions, which, it seems to me, requires habitat study (which
includes, in my mind, the UPS AND DOWNS (dynamics) of pollination,
dispersal
mechanisms, and soil factors--including nutrient dynamics, etc. Context
effects need to be considered, such as seasonal and site variations and,
this, I venture to assert, could be most important and perhaps all that
is
needed (at least for starters) the GROSS changes that can be observed
upon a
SINGLE sampling (again, for starters, but pregnant with possibilities,
even
though continued repeat samplings would be necessary [especially to
observe
trends and associated variables], perhaps for generations of students).
The
catch (22?) of course, would not only be getting funding, but getting
committee approval for such a "simple" study. I stand ready to be
corrected,
but it seems to me that the elegance of simplicity in research designs
has
been swamped by obfuscatory convolutions that "reach" (for) conclusions
that
seem to turn out to be self-ordained. I hope that subscribers will point
out
specific evidence to the contrary or otherwise assure me that this
phenomenon is at least not widespread, if not a figment of my
imagination.
CORRECTION: The statement in my earlier post: "I must admit that I had
not
thought much about evolutionary responses of (particularly) native plant
species until Bean's post, and I'm still thinking about it, but maybe
Bean
and others can expand my consciousness further on this particular topic."
should have read: "I must admit that I had not thought much about
evolutionary responses of (particular) native plant species until Bean's
post, and I'm still thinking about it, but maybe Bean and others can
expand
my consciousness further on this particular topic." I regret the errer. I
also apologize for mispelling Beans' name.
----- Original Message -----
From: Martin Meiss
To: Wayne Tyson
Cc: [email protected]
Sent: Thursday, April 08, 2010 6:18 AM
Subject: Re: [ECOLOG-L] Plants Invasive and Evolutionary response
Aliens?
Re: [ECOLOG-L] invasive and native plant competitors
While this seems an interesting and important area of study, I see
difficulties in making it an evolutionary study (as opposed to an
ecological
study). To me, an evolutionary study implies that you can compare gene
frequencies in a population BEFORE the invasion with frequencies AFTER
the
invasion. There are several problems with this: 1) How are you going to
sample gene frequencies from the 16 hundreds, which I'm guessing would be
about the time of the earliest invasions? 2) Even if you find a model
where
invasion happened this long ago, that doesn't seem like many generations
for
measurable change unless the interaction is very strong. 3) Assuming you
find measurable change, how will you know if it is caused by competition
with the invader, when there have been so many other environmental
changes
as a result of the invasion of European humans and the concomitant
changes
in land use patterns?
Just sampling present-day gene frequencies of populations with
and without invaders won't prove your case, since the populations might
have
had these differences before the invasion.
An ecological study, on the other hand, could look at shifts in
the geographical distribution of populations, where there may be
presence/absence data from old records. Also, you might be able to
elucidate the means/mode of competition (i.e., for pollinators,
dispersers,
habitat, use of soil minerals, etc.). Changes in morphology, as might be
revealed from old herbarium specimens, might reflect adaptive phenotypic
changes (without provable genetic basis) associated with habitat shifts,
though you would worry about whether old collections were statistically
representative of the old population.
Of course, Ms. Bean may have ways of addressing these issues,
and
perhaps other readers of this listserv can point out some solutions or
useful approaches (and, of course, possibly other problems).
Martin M. Meiss
2010/4/7 Wayne Tyson <[email protected]>
Howdy y'all:
I presume that Bean is referring to alien invasive species, but in the
purest sense, might one interpret the phenomenon more broadly? Indigenous
colonizers seem to be the orphans of the phenomenon, but might the
"evolutionary responses" to them be, in terms of evolutionary pressure,
more
"seasoned?"
I must admit that I had not thought much about evolutionary responses
of
(particularly) native plant species until Bean's post, and I'm still
thinking about it, but maybe Bean and others can expand my consciousness
further on this particular topic.
In a recent casual (insofar as they can be casual) trip to a
southwestern desert to observe the rampage of Brassica tournefortii, I
noticed some sharp "ecotones" between a depauperate-appearing Erodium
species and an indigenous indicator species, Lasthenia sp. (glabrata?).
The
indigenous species appeared to be succeeding better in the "poorer"
soils,
whilst the weedy alien (of long standing) seemed to be thriving in
apparently "better" soils. While this is nothing new, it may be an
under-studied phenomenon ripe for investigation. (This was an accidental
observation, however, while looking at a large colony of B. t.) Either of
these species would bear closer observations in a more disciplined way,
and
I suspect that funding might more readily be found for B. t. Apparently
Robin Marushia has been looking at B. t., and there are undoubtedly
others.
In my opinion, this species is a preeminent invader (not merely a ruderal
species), and extreme environments like deserts may be more instructive
places to work--especially if Bean wants to relocate and can find a
"slot"
someplace.
Just a thought . . .
WT
----- Original Message ----- From: "Carolyn Beans"
<[email protected]
>
To: <[email protected]>
Sent: Wednesday, April 07, 2010 7:39 AM
Subject: [ECOLOG-L] invasive and native plant competitors
Hello All,
I'm a first year graduate student and I'm planning to study the
evolutionary response of native plant
populations to an invasive plant competitor. Right now I'm at the
stage of trying to figure out exactly
which invasive and native plants to work with. I'm wondering if
anyone
has noticed any invasive
plants that seem to be especially strong competitors with a specific
native plant species? I would also
be interested in instances where an invasive plant appears to be
facilitating a native plant species.
I'll most likely be doing my field work in Virginia at Mountain Lake
Biological Station, but I could
potentially go anywhere.
thanks for your help!
Carolyn
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